Unlike traditional dyes such as DiBAC, FLIPR Membrane Potential Assay Kit detects bidirectional gradient changes so you can monitor both variable and control conditions within a single experiment. We recommend evaluating both assay kits to discern which formulation is right for your target.

FLIPR Membrane Potential Assay Kits detect ion channel modulation by increasing or decreasing the fluorescent signal as cellular membrane potential changes. The fluorescent signal increases in intensity during membrane depolarization as dye follows the positively charged ions inside the cell. During membrane hyperpolarization, fluorescent signal decreases in intensity as dye follows the positively charged ions out of the cell. The kits are uniquely suited for use with the simultaneous pipet and read capability of the FLIPR® Tetra System and FlexStation® 3 Microplate Readers to capture fast kinetics associated with ion channel activation.

The kits employ a quenching dye to reduce background fluorescence and improve the signal-to-noise ratio. The patented quench technology (U.S. patent number 6,420,183, EPO patent number 0 906 572) is offered to drug discovery and life science researchers exclusively by Molecular Devices through the purchase of FLIPR Assay Kits.

Comparison of Patch Clamp and FLIPR® Membrane Potential Assay Kit Data
The manual patch clamp method is able to detect fast responses allowing detection of very rapid changes in membrane potential. Comparing data generated using the FLIPR Membrane Potential Assay Kits with results from the manual patch clamp method shows good correlation (Figures 1 and 2). Both the opening and closing of the ion channel can be observed. This differs from DiBAC, which can only show unidirectional changes in membrane potential (Figure 3).

Two Membrane Potential Kit Quench formulations are available
Because ion channel activity is sensitive to interference, and chemical interference with a particular ion channel is highly unpredictable, the FLIPR Membrane Potential Assay Kits have two formulations. Both formulations combine the advantages of Molecular Devices proprietary membrane potential indicator dye with our patented quench technology. One formulation uses a blue quencher and the other formulation uses a red quencher. We recommend that both versions be evaluated for each individual target/cell line to determine which formulation will provide optimal performance.

Figure 4. Modulation of a Nav1.5 channel in CHL-hH1 cells by tetrodotoxin. In this assay, 30 mM veratridine is used to hold the sodium channel in its open state. Modulation occurs as tetrodotoxin concentration increases. A rapid influx of Na+ into the cell occurs, subsequently depolarizing the membrane, and leading to an increase in fluorescence. In this assay, the Membrane Potential Red Kit showed the larger signal window and larger Z factor.